Rotator cuff tears are a common cause of shoulder pain and dysfunction. Therefore, the purpose of this in-vitro biomechanical study was conducted to determine the effects of simulated tears and subsequent repairs of the rotator cuff tendons on joint kinematics. Eight paired fresh-frozen cadaveric shoulder specimens (mean age: 66.0 ± 8.7 years) were tested using a custom loading apparatus designed to simulate unconstrained motion of the humerus. Cables were sutured to the rotator cuff tendons and the deltoid. Loads were applied to the cables based on variable ratios of electromyographic (EMG) data and average physiological cross-sectional area (pCSA) of the muscles. An electromagnetic tracking device (Flock of Birds, Ascension Technologies, VT) was used to provide real-time feedback of abduction angle, to which the loading ratio was varied correspondingly. 2 and 4cm tears were made starting at the rotator cuff interval and extending posteriorly. Specimens were randomised to receive either single or double suture anchor repair. In order to quantify repeatability, five successive tests on each of the intact, torn, and repaired cases were performed. Statistical significance was established using One- and Two-way Repeated Measured ANOVAs (p< 0.05). Rotator cuff tears caused alteration in glenohumeral kinematics. A 2cm tear caused the humerus to consistently move posterior through the arc of abduction; however, as the tear increased to 4cm the humerus moved anteriorly, returning towards the intact state. Double row suture anchor repairs more accurately reproduced the kinematics of the intact specimen compared to single row suture anchor repair. The initial posterior displacement in the plane of elevation with the sectioning of the supraspinatus is related to the diminished anterior moment on the glenohumeral joint. As the tear proceeds into the infraspinatus, the anterior and posterior forces become more balanced and a return to near normal intact kinematics was observed. This study demonstrates that double row suture anchor repair more accurately reproduces active shoulder kinematics of the intact shoulder specimens

Introduction. We aim to assess whether radiographic characteristics of the greater tuberosity fragment can predict rotator cuff tears inpatients with anterior shoulder dislocations combined with an isolated fracture of the greater tuberosity. Methods. A retrospective single-centre case series of 61 consecutive patients that presented with anterior shoulder dislocations combined with an isolated fracture of the greater tuberosity between January 2018 and July 2022. Inclusion criteria: patients with atraumatic anterior shoulder dislocation associated with an isolated fracture of the greater tuberosity with a minimum follow-up of 3-months. Exclusion criteria: patients with other fractures of the proximal humerus or glenoid. Rotator cuff tears were diagnosed using magnetic resonance or ultrasound imaging. Greater tuberosity fragment size and displacement was calculated on plain radiographs using validated methods. Results. The case series was composed of 22 men and 39 women with a mean age of 65 years (29 - 91 years). The mean follow-up was 15months and median follow up 8.5 months (3 – 60 months). A rotator cuff tear was diagnosed in 14 patients (16%) and involved the supraspinatus (13), infraspinatus (4) and subscapularis (2). Full-thickness tears occurred in 6 patients and partial-thickness tears in 8patients. The mean time from initial injury to rotator cuff tear diagnosis was 5 months (2 – 22 months). The mean greater tuberosity fragment length was 23.4 mm in rotator cuff tear patients versus 32.6 mm in those without a tear (p = 0.006, CI: -15 - -2). The mean greater tuberosity. fragment width was 11.1 mm in rotator cuff tear patients versus 17.8 mm in those without a tear (p = 0.0004, CI: -10 - -2). There was no significant difference in the super inferior and anteroposterior fragment displacement between the two groups. Conclusion. In patients with shoulder dislocations combined with an isolated fracture of the greater tuberosity, rotator cuff tears are associated with a smaller sized greater tuberosity fragment

Massive rotator cuff tears associated with glenohumeral arthritis are currently an unsolvable clinical entity. This study strictly defines the use of bipolar hemiarthroptasty for the entity of RCTA. Materials – Methods: We review our series of 14 patients with Rotator Cuff Tear Arthropathy (RCTA) who underwent a bipolar prosthesis of their shoulder. The average follow up was 27.8 months (range 24–48 months) and the average age was 71 years old (range 57–84 years old), of these 14 patients there were 9 male and 5 female. None of these patients had previous shoulder surgery and all patients underwent conservative treatment that failed to improve their symptoms or range of motion. Results: Preoperatively the average forward flexion was 300, external rotation 100 and the American Shoulder and Elbow Society (ASES) score was 25 points. Postoperativety the average forward flexion improved to 880, external rotation increased to 370 and the ASES score improved to 80 pts, 12 of the 14 patients stated that they had no pain with activities of daily living. Two patients persisted to have moderate pain in everyday activity. Conclusion: We believe that bipolar hemiarthroplasty is currently a good option for treatment of Rotator Cuff Tear Arthropathy, The results of bipolar hemiarthroplasty provided more reliable pain relief than that for hemiarthroplasty

Rotator cuff tears are the most common cause of shoulder disability, affecting 10% of the population under 60 and 40% of those aged 70 and above. Massive irreparable rotator cuff tears account for 30% of all tears and their management continues to be an orthopaedic challenge. Traditional surgical techniques, that is, tendon transfers are performed to restore shoulder motion, however, they result in varying outcomes of stability and complications. Superior capsular reconstruction (SCR) is a novel technique that has shown promise in restoring shoulder function, albeit in limited studies. To date, there has been no biomechanical comparison between these techniques. This study aims to compare three surgical techniques (SCR, latissimus dorsi tendon transfer and lower trapezius tendon transfer) for irreparable rotator cuff tears with respect to intact cuff control using a clinically relevant biomechanical outcome of rotational motion. Eight fresh-frozen shoulder specimens with intact rotator cuffs were tested. After dissection of subcutaneous tissue and muscles, each specimen was mounted on a custom shoulder testing apparatus and physiologic loads were applied using a pulley setup. Under 2.2 Nm torque loading maximum internal and external rotation was measured at 0 and 60 degrees of glenohumeral abduction. Repeat testing was conducted after the creation of the cuff tear and subsequent to the three repair techniques. Repeated measures analysis with paired t-test comparisons using Sidak correction was performed to compare the rotational range of motion following each repair technique with respect to each specimen's intact control. P-values of 0.05 were considered significant. At 0° abduction, internal rotation increased after the tear (intact: 39.6 ± 13.6° vs. tear: 80.5 ± 47.7°, p=0.019). Internal rotation was higher following SCR (52.7 ± 12.9°, intact - SCR 95% CI: −25.28°,-0.95°, p=0.034), trapezius transfer (74.2 ± 25.3°, intact – trapezius transfer: 95% CI: −71.1°, 1.81°, p=0.064), and latissimus transfer (83.5 ± 52.1°, intact – latissimus transfer: 95% CI: −118.3°, 30.5°, p=0.400) than in intact controls. However, internal rotation post SCR yielded the narrowest estimate range close to intact controls. At 60° abduction, internal rotation increased after the tear (intact: 38.7 ± 14.4° vs. tear: 49.5 ± 13°, p=0.005). Internal rotation post SCR did not differ significantly from intact controls (SCR: 49.3 ± 10.1°, intact – SCR: 95% CI: −28°, 6.91°, p=0.38). Trapezius transfer showed a trend toward significantly higher internal rotation (65.7 ± 21.1°, intact – trapezius transfer: 95% CI: −55.7°, 1.7°, p=0.067), while latissimus transfer yielded widely variable rotation angle (65.7 ± 38°, intact – latissimus transfer: 95% CI: −85.9°, 31.9°, p=0.68). There were no significant differences in external rotation for any technique at 0° or 60° abduction. Preliminary evaluation in this cadaveric biomechanical study provides positive evidence in support of use of SCR as a less morbid surgical option than tendon transfers. The cadaveric nature of this study limits the understanding of the motion to post-operative timepoint and the results herein are relevant for otherwise normal shoulders only. Further clinical evaluation is warranted to understand the long-term outcomes related to shoulder function and stability post SCR

The shoulder girdle is an extremely mobile joint. Rotator cuff tears alter the existing equilibrium between bony structures and muscles. The “subacromial impingement syndrome” resulting from this unbalance leads to an extension of the rotator cuff lesion. Many authors have postulated a “mechanism of compensation”, but its existence still requires evidence. According to this model, the longitudinal muscles of the shoulder and the undamaged muscles of the rotator cuff would be able to functionally compensate, supersede the function of rotator cuff, and reduce symptoms. The aim of this study was to evaluate muscular activation of the medium fibers of deltoid, the superior fibers of pectoralis major, the latissimus dorsi and the infraspinatus by a superficial electromyographic study (EMG) and the analysis of kinematics in patients with a massive rotator cuff tear. We evaluated 30 subjects: 15 had pauci-symptomatic massive rotator cuff tear (modest pain and preserved movement), and 15 were healthy controls. Paired t-test showed significant different activations (p< 0.05) of these 4 muscles between the pathological joint and the healthy one in the same patient. The unpaired t-test, after comparing the mean EMG values of the 4 muscles, produced a significant difference (p< 0.05) between the experimental group and control group. This study showed that a mechanism of muscular compensation is activated in patients suffering from rotator cuff tear, involving the deltoid and the infra-spinatus muscle, as already presented in literature, but also demonstrated the activation of 2 other muscles: the latissimus dorsi and the pectoralis major. It is, therefore, probable that, in these patients, these muscles, which would not normally pull the head of the humerus downwards, adapt in order to compensate for the pathological situation. We believe that these data are valuable in the surgical and rehabilitation planning in patients with a massive rotator cuff tear

Glutamate regulates the expression of apoptosis-related genes and triggers the apoptosis of fibroblasts in rotator cuff tendons. Subacromial bursitis is always accompanied by symptomatic rotator cuff tear (RCT). However, no study has been reported on the presence of glutamate in subacromial bursa and on its involvement of shoulder pain in patients who had RCT. The purposes of this study were to determine whether the glutamate expression in subacromial bursa is associated with the presence of RCT and with the severity of shoulder pain accompanying RCT.

Subacromial bursal tissues were harvested from patients who underwent arthroscopic rotator cuff tendon repair or glenoid labral repair with intact rotator cuff tendon. Glutamate tissue concentrations were measured, using a glutamate assay kit. Expressions of glutamate and its receptors in subacromial bursae were histologically determined. The sizes of RCT were determined by arthroscopic findings, using the DeOrio and Cofield classification. The severity of shoulder pain was determined, using visual analog scale (VAS). Any associations between glutamate concentrations and the size of RCT were evaluated, using logistic regression analysis. The correlation between glutamate concentrations and the severity of pain was determined, using the Pearson correlation coefficient. Differences with a probability <0.05 were considered statistically significant.

Glutamate concentrations showed significant differences between the torn tendon group and the intact tendon group (P = 0.009). Concentrations of glutamate significantly increased according to increases in tear size (P < 0.001). In histological studies, the expressions of glutamate and of its ionotropic and metabotropic receptors have been confirmed in subacromial bursa. Glutamate concentrations were significantly correlated with pain on VAS (Rho=0.56 and P =0.01).

The expression of glutamate in subacromial bursa is significantly associated with the presence of RCT and significantly correlated with its accompanying shoulder pain.

Acknowledgements: This research was supported by the Basic Science Research Program, through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (NRF-2015R1D1A3A01018955 and 2017R1D1A1B03035232).

Purpose of the Study: We evaluated the results of surgical treatment for rotator cuff tears accompanied by proximal humerus fractures. Materials and Methods: Between September 2005 and April 2009, among a total of 103 patients undergoing surgical treatment with internal fixation for humerus fracture, 7 patients (6 females, 1 male; mean age 72.4 years; range 56 to 84years) underwent surgical treatment for rotator cuff tears accompanied by proximal humerus fracture. The mean follow-up period was 14 months (range 5 to 24 months). Radiographically, all fractures were classified according to the AO/ASIF system. AO/ASIF system type 11A2 accompanied by 12C2 (n:1), 11B1 (n:2), 11B2 (n:2), 11C2 (n:2). MRI was not used in any of the cases. All rotator cuff tears were determinated during the operation. Rotator cuff tears were repaired by primary suture (n:2), suture anchor (n:5), using the deltoid split approach (after treatment of proximal humerus fracture with open reduction and internal fixation. All patients used shoulder-arm sling for 6 weeks. Standard fracture rehabilitation was performed. Functional and radiographic results were evaluated. Results: None of the patients developed nonunion, implant failure or avascular necrosis. In the final evaluation, the Constant shoulder score was 82.8 (50–100). All patients were satisfied with results. Conclusion: The presence of rotator cuff tears in fractures of the proximal humerus is a especially possible in the elderly. Simultaneous repair of the fracture and rotator cuff does not create a negative functional and radiologic effect and prevents a future functional loss. Therefore the investigation of rotator cuff tears in all proximal humerus fractures and when present, treatment in the same session will increase the success of functional results

Purpose of the study: Little work has been done to assess outcome of rotator cuff tear repair in young adults aged less than 40 years. The purpose of our study was to assess the clinical and anatomic outcomes in a continuous series of arthroscopic rotator cuff repairs performed in patients aged less than 40 years. Material and method: This was a retrospective analysis (2004–2007) of 15 young patients (age 18–39 years, mean 32.7 years) with rotator cuff tears confirmed on the arthroscan. All tears were repaired arthroscopically using the same reinsertion technique with anchors. Patients underwent bilateral assessment (SSV, Constant) at at least 12 months follow-up. A control imaging with injection (arthroscan or arthroMRI) was available in 12 of 15 patients. Results: The series included 7 female and 8 male patients, 13 right and 2 left shoulders; 14 of 15 shoulders were on the dominant side. The time from symptom onset to surgery was 26 months on average. Patients were reviewed at mean 31 months follow-up. Preoperative range of motion was preserved in all patients. The mean preoperative Constant score was 55.5 on the operated side and 91.4 on the other side. The preoperative arthroscan demonstrated partial deep tears of the supraspinatus or infraspinatus in 5 patients with a posterosuperior impingement. The ten other shoulders exhibited full thickness tears of the supraspinatus. At last follow-up, the mean Constant score was 77.2 (range 44–90) with significant improvement of all partial scores except force. Patients resumed their former occupational activities at mean 8 months (range 1–36); resumption of sports activities occurred during the 7th month. Subjective satisfaction rate was 81.7%. Postoperative imaging with injection showed a healed cuff in 83% of the shoulders reviewed (10/12). Discussion: Rotator cuff tears are exceptional in young subjects aged less than 40 years; there is considerable potential for worsening. Outcome after rotator cuff repair is very age dependent. It is important to diagnose these tears early to enable early repair; the anatomic results are good and persistent in younger patients

Massive irreparable rotator cuff tears often lead to superior migration of the humeral head, which can markedly impair glenohumeral kinematics and function. Although treatments currently exist for treating such pathology, no clear choice exists for the middle-aged patient demographic. Therefore, a metallic subacromial implant was developed for the purpose of restoring normal glenohumeral kinematics and function. The objective of this study was to determine this implant's ability in restoring normal humeral head position. It was hypothesized that (1) the implant would restore near normal humeral head position and (2) the implant shape could be optimized to improve restoration of the normal humeral head position.

A titanium implant was designed and 3D printed. It consisted of four design variables that varied in both implant thickness (5mm and 8mm) and curvature of the humeral articulating surface (high constraint and low constraint. To assess these different designs, these implants were sequentially assessed in a cadaver-based biomechanical testing protocol. Eight cadaver specimens (64 ± 13 years old) were loaded at 0, 30, and 60 degrees of glenohumeral abduction using a previously developed shoulder simulator. An 80N load was equally distributed across all three deltoid heads while a 10N load was applied to each rotator cuff muscle. Testing states included a fully intact rotator cuff state, a posterosuperior massive rotator cuff tear state (cuff deficient state), and the four implant designs. An optical tracking system (Northern Digital, Ontario, Canada) was used to record the translation of the humeral head relative to the glenoid in both superior-inferior and anterior-posterior directions.

Re-rupture rates after rotator cuff repair remain high because of inadequate biological healing at the tendon-bone interface. Single-growth factor therapies to augment healing at the enthesis have so far yielded inconsistent results. An emerging approach is to combine multiple growth factors over a spatiotemporal distribution that mimics normal healing. We propose a novel combination treatment of insulin-like growth factor 1 (IGF-1), transforming growth factor β1 (TGF-β1) and parathyroid hormone (PTH) incorporated into a controlled-release tyraminated poly-vinyl-alcohol hydrogel to improve healing after rotator cuff repair. We aimed to evaluate this growth factor treatment in a rat chronic rotator cuff tear model.

A total of 30 male Sprague-Dawley rats underwent unilateral supraspinatus tenotomy. Delayed rotator cuff repairs were then performed after 3 weeks, to allow tendon degeneration that resembles the human clinical scenario. Animals were randomly assigned to: [1] a control group with repair alone; or [2] a treatment group in which the hydrogel was applied at the repair site. All animals were euthanized 12 weeks after rotator cuff surgery and the explanted shoulders were analyzed for biomechanical strength and histological quality of healing at the repair site.

In the treatment group had significantly higher stress at failure (73% improvement, P=0.003) and Young's modulus (56% improvement, P=0.028) compared to the control group. Histological assessment revealed improved healing with significantly higher overall histological scores (10.1 of 15 vs 6.55 of 15, P=0.032), and lower inflammation and vascularity.

This novel combination growth factor treatment improved the quality of healing and strength of the repaired enthesis in a chronic rotator cuff tear model. Further optimization and tailoring of the growth factors hydrogel is required prior to consideration for clinical use in the treatment of rotator cuff tears. This novel treatment approach holds promise for improving biological healing of this clinically challenging problem.

Interstitial supraspinatus tears can cause persistent subacromial impingement symptoms despite non operative treatment. Autologous tendon cell injection (ATI) is a non-surgical treatment for tendinopathies and tear. We report a randomised controlled study of ATI compared to corticosteroid injection (CS) as treatment for interstitial supraspinatus tears and tendinopathy.

Inclusion criteria were patients with symptom duration > 6 months, MRI confirmed intrasubstance supraspinatus tear, and prior treatment with physiotherapy and ≥ one CS or PRP injection. Participants were randomised to receive ATI to the interstitial tear or corticosteroid injection to the subacromial bursa in a 2:1 ratio, under ultrasound guidance. Assessments of pain (VAS) and function (ASES) were performed at baseline, and 1, 3, 6 and 12 months post treatment.

30 participants (19 randomised to ATI) with a mean age of 50.5 years (10 females) and a mean duration of symptoms of 23.5 months. Baseline VAS pain and ASES scores were comparable between groups. While mean VAS pain scores improved in both groups at 3 months after treatment, pain scores were superior with ATI at 6 months (p=0.01). Mean ASES scores in the ATI group were superior to the CS group at 3 months (p=0.026) and 6 months (p=0.012). Seven participants in the CS group withdrew prior to 12 months due to lack of improvement. At 12 months, mean VAS pain in the ATI group was 1.6 ± 1.3. The improvements in mean ASES scores in the ATI group at 6 and 12 months were greater than the MCID (12.0 points). At 12 months, 95% of ATI participants had an ASES score > the PASS (patient acceptable symptom state).

This is the first level one study using ATI to treat interstitial supraspinatus tear. ATI results in a significant reduction in pain and improvement in shoulder function.

Introduction and Objective

Only few studies have investigated the outcome of exercises in patients with glenohumeral osteoarthritis (OA) or rotator cuff tear arthropathy (CTA), and furthermore often excluded patients with a severe degree of OA. Several studies including a Cochrane review have suggested the need for trials comparing shoulder arthroplasty to non-surgical treatments. Before initiation of such a trial, the feasibility of progressive shoulder exercises (PSE) in patients, who are eligible for shoulder arthroplasty should be investigated. The aim was to investigate whether 12 weeks of PSE is feasible in patients with OA or CTA eligible for shoulder arthroplasty. Moreover, to report changes in shoulder function and range of motion (ROM) following the exercise program.

Patients over 70 years old have subclinical or impending rotator cuff dysfunction, raising concern about TSA in this population. The purpose of this study is to examine whether reverse total shoulder arthroplasty (RTSA) should be considered for the treatment of glenohumeral osteoarthritis in the presence of an intact rotator cuff (GHOA+IRC in patients older than 70 years of age.

Twenty-five elderly (>70 years) patients at least one year status-post RTSA for GHOA+IRC were matched via age, sex, body mass index, smoking status, and whether the procedure involved the dominant extremity with 25 GHOA+IRC patients who received anatomic total shoulder arthroplasty (TSA). Standardised outcome measures, range of motion, and treatment costs were compared between the two groups. Treatment cost was assessed using implant and physical therapy costs as well as reimbursement.

Patients who received RTSA for GHO+IRC had significantly lower pre-operative active forward elevation (AFE, 69° vs. 98°, p <0.001) and experienced a greater change in AFE (p=0.01), but had equivalent AFE at final follow-up (140° vs. 142°, p=0.71). Outcomes were otherwise equivalent between groups with no differences. In both those patients who underwent TSA and those that underwent RTSA, significant improvements between pre-operative and final follow-up were seen in all standardised outcome measures and in AFE (p<0.001 in all cases). RTSA provided these outcomes at a cost savings of $2,025 in Medicare reimbursement due to decreased physical therapy costs.

In patients over the age of 70 with GHOA+IRC, RTSA provides similar improvement in clinical outcomes to TSA at a reduced cost while avoiding issues related to the potential for subclinical or impending rotator cuff dysfunction.

The management of patients with massive irreparable rotator cuff tears (RCT) has traditionally proved challenging. This prospective study was undertaken with the aim to assess the overall functional outcome following the use of human dermal allograft in the reconstruction of massive irreparable RCT.

15 patients were included in the study, having a median age of 63 years. All patients underwent open reconstruction of massive irreparable RCT. None of the selected patients had evidence of significant gleno-humeral arthritis. All patients were evaluated pre- and post- operatively by the treating surgeon, and followed up for 12 months. The same physiotherapy protocol was prescribed for all patients. Initial and follow-up assessments were done at regular intervals using the Oxford and quick-DASH scoring systems.

A very high patient satisfaction rate, with substantial improvement in pain and function was noted. There was substantial improvement in Oxford shoulder score from a mean of 23.3 to 8.7 (p<0.01), and a similar improvement in mean quick-DASH score from 50.3 to 23.0 (p<0.01)

Of the 15 patients, 11 had an improvement of >10 in Oxford score, with these reporting a score of <10 after 12 months. None of the patients had any significant complications because of the surgery, and none had a deterioration in Oxford score from their pre-operative status.

We found that Human dermal allograft is a very effective tool in the repair of massive irreparable RCT, with excellent follow-up results after one year.

Anatomy of the rotator cuff tendons, their relationship to the greater tuberosity, and the tensile and compressive properties of the cuff tendons have been extensively studied recently. From these anatomical and biomechanical studies, it has been clarified that stress concentration at the anterior portion of the supraspinatus tendon, shearing force, and mechanical friction as well as the degenerative weakness of the cuff tendons can all play a role in the occurrence of a tear. Strength of initial repair is limited, and thus the arm after repair should be positioned such that undue tension at the repair site is eliminated.

Background:

Massive rotator cuff tear can cause functional disability due to instability and degenerative changes of the shoulder joint. In patients with massive irreparable rotator cuff tear, tendon transfer is often used as the salvage procedure. Latissimus dorsi and pectoris major transfer are technically demanding procedures and may incur complications. The biceps tendon transfer may provide a biologically superior tissue patch that improves the biomechanics of the shoulder joint in patients with irreparable rotator cuff tear. This study evaluated the functional outcomes of biceps tendon transfer for irreparable rotator cuff tear in 6 patients with two years and longer follow-up.

Disuse osteoporosis of the greater tuberosity is a consequence of rotator cuff tear. This is a significant problem as the tendon is implanted into a trough within the greater tuberosity during repair. Failure of the repair is a common complication (up to 50%). We hypothesized that failure in re-implantation is due to deficient bone cell response to mechanical stimulation in the tuberosity. In order to establish whether these cells are capable of responding appropriately to mechanical stimuli, the response of bone cells derived from the tuberosity was compared with that of cells derived from the acromion. This was measured in terms of strain related increases in alkaline phosphatase (ALP) activity, nitric oxide (NO) and prostaglandin (PG) production (which are recognised markers of osteoblast differentiation and their response to mechanical strain).

Primary osteoblasts were cultured from samples of acromion and greater tuberosity taken during routine rotator cuff repair (n=5 pairs). The derived cells were placed under cyclic strain at a physiological magnitude for 10 min at 1Hz using well established controls. Samples of media were analysed for changes in NO and PG production and the cells were reacted for ALP. Cells were stimulated with dexamethasone, ascorbic acid and beta-glycerophosphate (established mediators of osteoblast differentiation) then reacted for ALP.

Preliminary results suggest that cells derived from the acromion exhibit significant increases in cellular NO release and in ALP activity, whereas cells derived from the humeral greater tuberosity fail to exhibit any such increases. In marked contrast cells derived from both sites exhibit increases in ALP activity in response to dexamethasone, ascorbic acid and beta-glycerophosphate treatment.

The results suggest that whilst cells derived from the tuberosity after rotator cuff tear respond appropriately to chemical and hormonal stimuli, they are compromised in their ability to respond to mechanical stimulation. It is tempting to speculate that such relationships are also evident in vivo and that they underpin reimplantation failures.

In 1990, after many years of experience with 150 repairs, an arthroscopic transhumeral rotator cuff reconstruction technique was developed and used by the authors to treat all sizes of rotator cuff tears. This technique allowed the same type of repair to be performed as with the open procedure, thus providing the possibility to achieve the same success rate as an open repair with the advantages of minimally invasive surgery.

We reviewed a total of 307 arthroscopic rotator cuff repair procedures performed on 304 patients between December 1990 and March 1994. There were 150 cases with arthroscopic transhumeral fixation and 157 with tendon end-to-end. Of the 150 transhumeral repair cases studied, 18 cases were traumatic, 124 were Impingement III tears, and eight were defects after calcium removal. The tears were classified as 42 – small, 66 – medium, and 42 – large. Average age was 56 years.

An anterior acromioplasty and an arthroscopic tendon to bone repair using the bone cutting giant needle was performed in all of the cases. An AC joint plasty was done in 20 cases and a tendon transposition in five cases. Postoperatively, the patients started full passive motion a day after surgery and active motion six weeks later.

Of the 150 cases with arthroscopic transhumeral repair cases, it was possible to evaluate 132 patients having 133 procedures. Mean follow-up was five years. The results were evaluated according to the classification of Neer. There were 64% classified as excellent, 34% as satisfactory, and 2% as unsatisfactory. The UCLA average score improved from 15.8 preoperatively to 31.5 postoperatively. Full reconstruction was done in all cases except three.

Arthroscopic transhumeral reconstruction of rotator cuff tear reduces morbidity without having to perform open surgery. This procedure can be performed in an outpatient setting. After the learning curve, repairs are easier than the open method and have fewer complications.

Introduction

Rotator cuff healing after an arthroscopic repair is discussible because of the high incidence of failures. Among biologic augmentations currently used, platelet-rich plasma (PRP) is one of the most applied, supposed to enhance and accelerate the healing process in different musculoskeletal disorders. However, the evidence supporting its successful administration is still lacking, especially in the field of the rotator cuff repair. Our purpose is to clarify if the recovery is accelerated and the integrity of repaired construct is increased in patients undergoing PRP injections after arthroscopic repair of the rotator cuff.

Disturbed muscular architecture, fatty infiltration and muscular atrophy remain irreversible in chronic rotator cuff tears (RCT) even after repair. Poly-[ADP-ribose]-polymerase 1 (PARP-1), a nuclear factor involved in DNA damage repair, has shown to be a key element in the up-regulation of early muscle inflammation, atrophy and fat deposition. We therefore hypothesized that the absence of PARP-1 would lead to a reduction in muscular architectural damage, early inflammation, atrophy and fatty infiltration subsequent to combined tenotomy and neurectomy in a PARP-1 knock-out mouse model.

PARP-1 knock-out (KO group) and standard wild type C57BL/6 (WT group) mice were randomly allocated into three different time points (1, 6 and 12 weeks, total n=72). In all mice the supraspinatus (SSP) and infraspinatus (ISP) tendons of the left shoulder were detached and the SSP muscle was denervated according to a recently established model. Macroscopic muscle weight analysis, retraction documentation using macroscopic suture, magnetic resonance imaging, immunohistochemistry gene expression analysis using real time qPCR (RTqPCR) and histology were used to assess the differences in muscle architecture, early inflammation, fatty infiltration and atrophy between knock out and wild type mice in the supraspinatus muscle.

The SSP did retract in both groups, however; the KO muscles and tendons retracted less than the WT muscles (2.1±21mm vs 3.4±0.41mm; p=0.02). Further assessment of muscle architecture demonstrated that the pennation angle was significantly higher in the KO groups at 6 and 12 weeks (28±5 vs 36±5 and 29±4 vs 34±3; p<0.0001). Combined Tenotomy and neurectomy resulted in a significant loss of muscle mass in both groups compared to the contralateral unoperated side (KO group 62±11% and WT group 52±11%, p=0.04) at 6 weeks. But at 12 weeks postoperatively, there was a significant increase in muscle mass to near normal levels in KO group compared to the WT group (14±6% and 42±7% lower muscle mass respectively; p<0.0001) and less fatty infiltration (12.5 ± 1.82% and 19.6 ± 1.96%, p=0.027). Immunohistochemistry revealed a significant decrease in the expression of inflammatory, apoptotic, adipogenic and muscular atrophy genes at both the 1 week and 6 weeks time points, but not at 12 weeks in the KO group compared to the WT group. This was confirmed by histology.

Our study is the first to show that knocking out PARP-1 leads to decreased loss of muscle architecture, early inflammation, fatty infiltration and atrophy after combined tenotomy and neurectomy of the rotator cuff muscle. Although the macroscopic muscles reaction to injury is similar in the first 6 weeks, its ability to regenerate is much greater in the PARP-1 group leading to a near normalization of the muscle substance and muscle weight, less retraction, and less fatty infiltration after 12 weeks.